I think that wire was tagged as the amp remote. It's a JVC KD-S100 it has 6 channels - four tuned to 5V and two @ 2V(subs). I can't wait to get'em in. Taking a week vacation next month. Going to do the Big 3, build a sub box, deaden....Hoping to be ready as can, totally stoked. I'll take pictures but am sh***y with a computer. lol.